Re: [Xen-devel] [RFC PATCH 00/19] xen/arm: Add ITS support

[Vijay Kilari <vijay.kilari@xxxxxxxxx>]

Hi Julien,

On Mon, Mar 2, 2015 at 6:49 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> Hi Vijay,
>
> On 02/03/15 12:30, vijay.kilari@xxxxxxxxx wrote:
>> From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>
>>
>> Add ITS support for arm. Following major features
>> are supported
>>  - GICv3 ITS support for arm64 platform
>>  - Supports only single ITS node
>
> Why only one ITS node supported? I though Cavium was using 2 ITS...

I will update for 2 ITS nodes later when NUMA is supported

>
>>  - LPI descriptors are allocated on-demand
>>  - Only ITS Dom0 is supported
>
> Any plan to support guest?

Yes, I will do it in next version

>
>> Vijaya Kumar K (19):
>>   xen/arm: add linked list apis
>>   xen/arm: its: Import GICv3 ITS driver from linux
>>   xen/arm: its: Port ITS driver to xen
>
> A general comment (I haven't read closely the patches). The GICv3 ITS
> taken from Linux is modified so heavily (rename function, move out code,
> dropping unused code...) that your assumption in patch #1 [1] is wrong.
>
> At the end of this series it would make impossible to backport patch
> from Linux.

  Most of the code is reused or moved to different file based on Xen
requirement.
    - code like msi registered callback (setup_irq & teardown_irq) is of
no use in Xen. So removed
    - irq_chip is different in linux
    - some of the functions like encode of ITS commands can be used in
virtual ITS
      driver as well. So have to be moved out to header file
    - the LPI allocation is moved to virtual ITS driver. We can
consider it keeping in physical ITS
      driver but it fits well in virtual ITS driver rather than
physical ITS driver.


>
> Regards,
>
> [1] "This is actual GICv3 ITS driver from Linux. [..] This helps to
> import any issues found in Linux"

I have kept the linux GICv3 ITS driver in first patch and made incremental
changes just to have better understanding and incremental approach

Regards
Vijay

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